The greatest environmental risk to human spaceflight beyond the
Earth’s magnetosphere is radiation. Ionizing radiation, galactic
cosmic radiation (GCR), and solar cosmic radiation (SCR), is
a significant risk to astronauts for all long-duration missions beyond
LEO regardless of destination (NEO, lunar surface, or Mars). Many
of these high energy elementary particles penetrate spacecraft, pressure
vessels and space suits (generating secondary radiation particles
in the process) as well as organs, cells and DNA of human occupants
inducing degenerative changes usually associated with accelerated
aging (extracellular matrix remodeling, persistent inflammation,
oxidative damage, cataracts and damage to the central nervous system).
DNA damage results in increased mutation rates, genomic instability,
cancer induction and activation of latent tumors. Effective strategies
for mitigating space radiation hazards must be developed, tested
and verified if mission success is to be assured. Technologies for
shielding approaches such as placement of equipment, food, water
and waste material in long-duration spacecraft; polyethylene lined
sleep stations or internal ‘shelters;’ external shielding approaches
such as storable propellant placement, use of NEO regolith ‘sandbagging’
to protect crew compartment(s) during proximity ops and return phases
of the mission, radio-protective pharmaceuticals (TA06) that could
be taken as a preventive or in response to a significant increase
in radiation (such as an SPE) and plastics/polymers need to be developed
and tested.